Effect of Rubber Polarity on Cluster Formation in Rubbers Cross-Linked with Diels–Alder Chemistry

Polgar, Lorenzo Massimo; Hagting, Erik; Raffa, Patrizio; Mauri, Michele; Simonutti, Roberto; Picchioni, Francesco; Duin, Martin van

doi:10.1021/acs.macromol.7b01541

Cited by 36 publications

(34 citation statements)

References 45 publications

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“…Crosslink density ν (mol/cm 3 ) of each vulcanized compound was calculated by applying the Flory–Rehner equation for tetrafunctional networks [eq. ]:

ν = - \frac{1}{2 V_{s}} \frac{\ln ((), 1 - V_{r}) + V_{r} + χ V_{r}^{2}}{(V_{r}^{\frac{1}{3}} - 0.5 V_{r})}

…”

Section: Methodsmentioning

confidence: 99%

Effect of co‐agents on adhesion between peroxide cured ethylene–propylene–diene monomer and thermoplastics in two‐component injection molding

Laing

Keyzer

Seveno

et al. 2019

J of Applied Polymer Sci

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injection-molded products combining ethylene-propylene-diene monomer (EPDM) with polar or nonpolar thermoplastics require strong interfacial bonding. To optimize the adhesion, co-agents trimethylolpropane trimethacrylate (TMPT) and triallyl cyanurate (TAC) are compared and concentrations were varied between 0 and 12 parts per hundred rubber (phr). Changes in material compatibility were characterized by contact angle measurements at high temperature, the adhesion was evaluated by tensile testing, and physicomechanical properties of the EPDM bulk were analyzed. Results show that with polypropylene, the adhesion increases to an optimum (3 phr TAC or 6 phr TMPT) independent of the co-agent type, while for polyethylene only TAC (1.5 phr) effectively boosts adhesion. It is surmised that these optimal concentrations promote crosslinking reactions at the interface. For polycarbonate and acrylonitrile-butadiene-styrene, increasing TAC concentration causes higher adhesion due to improved compatibility. Furthermore, physicomechanical bulk properties change significantly with co-agent concentrations, making the optimal curing composition application dependent.

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“…Crosslink density ν (mol/cm 3 ) of each vulcanized compound was calculated by applying the Flory–Rehner equation for tetrafunctional networks [eq. ]:

ν = - \frac{1}{2 V_{s}} \frac{\ln ((), 1 - V_{r}) + V_{r} + χ V_{r}^{2}}{(V_{r}^{\frac{1}{3}} - 0.5 V_{r})}

…”

Section: Methodsmentioning

confidence: 99%

Effect of co‐agents on adhesion between peroxide cured ethylene–propylene–diene monomer and thermoplastics in two‐component injection molding

Laing

Keyzer

Seveno

et al. 2019

J of Applied Polymer Sci

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“…The difference was confirmed by SAXS. The different mechanical properties between the two materials were interpreted on the basis of the homogeneity (or lack thereof) of the network [47]. Another strategy to allow recyclability and, at the same time, allowing for use in a biomedical application is the use of biocompatible prepolymer.…”

Section: Discovery and Characterization Of New Materialsmentioning

confidence: 99%

Time Domain NMR in Polymer Science: From the Laboratory to the Industry

2019

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Highly controlled polymers and nanostructures are increasingly translated from the lab to the industry. Together with the industrialization of complex systems from renewable sources, a paradigm change in the processing of plastics and rubbers is underway, requiring a new generation of analytical tools. Here, we present the recent developments in time domain NMR (TD-NMR), starting with an introduction of the methods. Several examples illustrate the new take on traditional issues like the measurement of crosslink density in vulcanized rubber or the monitoring of crystallization kinetics, as well as the unique information that can be extracted from multiphase, nanophase and composite materials. Generally, TD-NMR is capable of determining structural parameters that are in agreement with other techniques and with the final macroscopic properties of industrial interest, as well as reveal details on the local homogeneity that are difficult to obtain otherwise. Considering its moderate technical and space requirements of performing, TD-NMR is a good candidate for assisting product and process development in several applications throughout the rubber, plastics, composites and adhesives industry.

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“…59,60,6162,63,64,65 For thermo-reversible covalent networks, van Duin and collaborators recently unveiled micro-phase separation in ethylene/propylene rubbers crosslinked with a dissociative Diels-Alder chemistry. 66 In polymer covalent networks, macroscopic phase separation can also occur as a result of entropic effects. Indeed, when the crosslink density is sufficiently high, the presence of even good solvent may cause the network to undergo a syneresis.…”

Section: Introductionmentioning

confidence: 99%

Phase Separation and Self-Assembly in Vitrimers: Hierarchical Morphology of Molten and Semicrystalline Polyethylene/Dioxaborolane Maleimide Systems

2018

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Vitrimers -a class of polymer networks which are covalently crosslinked and insoluble like thermosets, but flow when heated like thermoplastics -contain dynamic links and/or crosslinks that undergo an associative exchange reaction. These dynamic crosslinks enable vitrimers to have interesting mechanical/rheological behavior, self-healing, adhesive, and shape memory properties.We demonstrate that vitrimers can self-assemble into complex meso-and nanostructures when crosslinks and backbone monomers strongly interact. Vitrimers featuring polyethylene (PE) as the backbone and dioxaborolane maleimide as the crosslinkable moiety were studied in both the molten and semi-crystalline states. We observed that PE vitrimers macroscopically phase separated into dioxaborolane maleimide rich and poor regions, and characterized the extent of phase separation by optical transmission measurements. This phase separation can explain the relatively low insoluble fractions and overall crystallinities of PE vitrimers. Using synchrotronsourced small-angle X-ray scattering (SAXS), we discovered that PE vitrimers and their linear precursors micro-phase separated into hierarchical nanostructures. Fitting of the SAXS patterns to a scattering model strongly suggests that the nanostructures -which persist in both the melt and amorphous fraction of the semi-crystalline state -may be described as dioxaborolane maleimide rich aggregates packed in a mass fractal arrangement. These findings of hierarchical meso-and nanostructures point out that incompatibility effects between network components and resulting self-assembly must be considered for understanding behavior and the rational design of vitrimer materials.Thermoplastics and thermoplastic elastomers are soluble in good solvents and flow when heated above the glass or melting temperature. Thermosets and rubbers do not flow and are not soluble.Vitrimers, a class of polymers introduced by Leibler and collaborators in 2011, flow when heated, but remain insoluble. 1 Vitrimers are made of polymer networks which contain covalent crosslinks that undergo dynamic associative exchange reactions. The covalent crosslinks in a vitrimer maintain network connectivity at all times and temperatures. Unlike materials employing dissociative crosslinking mechanisms, 2 vitrimers cannot be completely dissolved -even in good solvents. 1,3 Associative exchange reactions permit the network topology to fluctuate and the system to flow when stress is applied, and exchange reaction kinetics control the vitrimer relaxation dynamics and viscosity. 2,4,5,6 The initial reports of vitrimer systems focused on epoxy networks that reorganized via metal-catalyzed transesterification. 1,4,6 Today, the library of dynamic exchange reactions has expanded to include chemistries that are catalytically-controlled (olefin metathesis and transcarbonation) 7,8 or catalyst-free (transamination, 9,10,11 trans-N-alkylation, 12,13 reversible addition of thiols, 14 imine exchange, 15,16 addition-fragmentation chain transfer, 17,18 boronic est...

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Effect of Rubber Polarity on Cluster Formation in Rubbers Cross-Linked with Diels–Alder Chemistry

Cited by 36 publications

References 45 publications

Effect of co‐agents on adhesion between peroxide cured ethylene–propylene–diene monomer and thermoplastics in two‐component injection molding

Effect of co‐agents on adhesion between peroxide cured ethylene–propylene–diene monomer and thermoplastics in two‐component injection molding

Time Domain NMR in Polymer Science: From the Laboratory to the Industry

Phase Separation and Self-Assembly in Vitrimers: Hierarchical Morphology of Molten and Semicrystalline Polyethylene/Dioxaborolane Maleimide Systems

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